In this article you will learn how allergy affects the immune system. You will begin to understand how and why certain people become allergic. The most common allergic diseases are briefly discussed in this article.
What does an average allergy do?
An allergy refers to an exaggerated reaction of our immune system in response to physical contact with certain foreign substances. It is sometimes strange to comprehend. These foreign substances are usually perceived by the body as harmless and cause no reaction for non-allergic people. Anti-producing substances are so-called “allergens.” Examples of allergens are pollen, dust mites, mold, dander and food. To understand the language of allergy it is important to remember that allergens are substances that are foreign to the body and can cause an allergic reaction in some people.
When an allergen comes into contact with the body, it causes the immune system to respond with an allergic response in individuals who are allergic to a particular substance. If you have inappropriate reactions to allergens that are normally harmless to other people, you are having an allergic reaction and may be referred to as allergic or atopic. Therefore, people who are prone to allergies; allergic or “atopic.”
Austrian pediatrician Clemens Pirquet (1874-1929) first used the term allergy. He refers to both the beneficial immunities and the harmful hypersensitivity as “allergy.” The word allergy is derived from the Greek words “allos,” different meaning or modified, and “ergos,” meaning work or occupation. Anti roughly refers to an “altered response.” The word allergy was first used in 1905.
- It is estimated that 50 million North Americans are affected by allergic conditions.
- The cost of allergies in the United States is more than $10 billion dollars per year.
- Allergic rhinitis (nasal allergies) affects approximately 35 million Americans, 6 million of whom are children.
- Asthma affects 15 million Americans, 5 million of whom are children.
- The number of asthma cases has doubled in the past 20 years.
What causes allergies?
To answer this question, let’s first look at a common household example. A few months after the new cat arrives in the house, Dad starts having itchy eyes and sneezing. One out of three children develops coughing and wheezing, especially when the cat comes into a bedroom. The mother and the other two children experience no reaction to the presence of the cat. How can we explain this?
The immune system
The immune system is an organized defense mechanism in the body against foreign invaders, especially infections. Its task is to recognize and respond to foreign substances, so-called antigens. Antigens are substances that cause the production of antibodies. The antigens may not or may not lead to an allergic reaction. Allergens are certain antigens that lead to an allergic reaction and the production of IgE.
IgE: Immunoglobulin E
IgE: Immunoglobulin E, a class of immunoglobulins that includes the antibodies caused by an allergic substance (allergen). A person who has an allergy usually has elevated blood levels of IgE. IgE antibodies attack and turn off the invading army of allergens. The E in IgE stands for erythema (redness).
The purpose of the immune system is to mobilize its forces to destroy the enemy. One of the ways to create this comes from protective proteins called antibodies that specifically target particularly foreign substances. The allergic person, however, develops a specific type of antibody, called immunoglobulin E or IgE, in response to certain normally harmless foreign substances, such as cat dander. To summarize, immunoglobulins are a group of protein molecules that act like antibodies. There are five different types; IgA, IgM, IgG, IgD and IgE. IgE is the allergy antibody.
In the cat, for example, the father and youngest daughter developed IgE antibodies in large amounts that were directed against the cat allergen, cat dander. The father and daughter are now susceptible or prone to developing allergic reactions on subsequent and repeated exposure to cat allergen. Typically, there is a period of “hypersensitivity” ranging from months to years prior to an allergic reaction.
IgE is an antibody that we all have in small amounts. However, allergic individuals produce IgE in excessive amounts. Normally this antibody is important and protects us against parasites, but not from cats or dander or other allergens. During the period of sensitization, cat dander IgE is overproduced and coats certain explosive cells that contain chemicals. These cells can cause an allergic response to subsequent exfoliation of the dander. This is due to the cat’s reaction to the dander. IgE irritates the cells and leads to the release of various chemicals, including histamine. These chemicals are in turn the cause of inflammation(s) and the typical allergic symptoms.
On exposure to cat dander, the mother and the other two children produce different classes of antibodies, none of which cause allergic reactions. In these non-allergic members of the family, the dandruff particles are eliminated by the immune system and the cat has no effect on them.